Flat roof: epdm vs tpo?

Hi, I’m hoping for advice on replacement roofing. I live in the middle midwest…hot summers, cold winters. My home is a mid-century modern designed by my late father. Currently it has an epdm roof over 20 years old that was too thin to begin with. When it rains you can’t talk on the phone or hear the TV. Still, if it could be covered with another epdm layer maybe it wouldn’t be so bad. I’m also considering tpo. This house needs a whole lot of other repairs and maintenance, so cost is very much a factor. I realize contractors will promote what they use. Could someone give me objective pros and cons?



The noise you hear could easily be mitigated by just adding some polyisocyanurate insulation or 5/8" Dens Deck and then re-roofing. If the EPDM has performed well, I would continue to use it on a new roof. Use a minimum of 060 mil thickness this time. If you have heat problems with the roof, consider switching to TPO to help with that problem. I understand the cost issue, but keep in mind that without a good roof your other repairs will not mean much when water runs into your home.

Thank you, donl. Are you saying the EPDM could be laid with a layer of insulation over the old roofing material?

If you only have one original roof, the old EPDM membrane can be left in place IF you slice it up to prevent any moisture being trapped between new and old membrane. If your original system is mechanically fastened to the deck (not glued), just cut the membrane and remove the loose membrane leaving the fasteners and a small amount of membrane in place before installing a new system.
One other thing, are you saying that the original membrane is installed directly to the deck? If so, you have no fire rating. If that is the case you will need to install a thermal barrier under the new membrane.

I have pretty extensive experience with both, and have worked for manufacturers of both products. Both are good products, that frankly come down to the contractor installing them. The trend in the Midwest and most of the nation is towards TPO and away from EPDM. In general, TPOs are easier to retrofit for future solar, have stronger (welded) seams and flashings. But EPDM can be manufactured in larger sheets that can often eliminate seams all together. The only things I really don’t like about EPDM are: the uncured flashings seem to dry out prematurely, if the roof is installed in any way other the fully adhered- the membrane shrinks quite a bit. And probably 80% of EPDM out there is unreinforced and easy to puncture…

TPO eliminates most of these shortcomings.
But both are good roof membranes.

Thanks, donl. This was my parents’ house and I’m not sure when they had the EPDM put on cause I wasn’t living here. I think it’s pretty old…maybe the early 90’s? That being said, I do remember a marked increase in rain noise when I came to visit or talking on the phone. I remember thinking, wow, that new roof must be thin. In the 10 years I’ve been living here it’s shrunk from the edges and I’ve had to have some patching because of a leaks at a corner.

I’m concerned about structural integrity, as the ceiling is wood beams and unfinished planks, a mid-century “post-and-beam” house similar to Eichlers out in California. This is a ceiling that could not easily be replaced. So now I’m thinking, rather than another layer of roofing, I should probably have the old roofing removed to get a look at how the beams and wood plank ceiling are holding up. I’ve got carpenter ants and their debris at corners that concerns me.

This all sounds extremely expensive. Without getting into possible structural issues that could be discovered beneath the roofing surface, could anyone give me an expectable ballpark figure for removal and replacement with EPDM or TPO for 31.5’ x 59’?

(btw…meanwhile the old-fashioned modified bitumen roof on the detached garage is at least as old and holding up just fine. Sometimes I wonder…but would be scared off by fire hazard for a primary residence, I guess.)

thanks for any input!!!

Hi guys. Thanks in advance for your time and professional advice!

It’s been awhile since I posted the original question here. I spent the last few years fixing up and selling my former home. Now I’m back to having to make a roofing decision on my own home. I’ve met with 8 local roofers. Learning about roofs has been a steep curve education and I still don’t feel I know enough to make a decision. Bids so far have ranged from $6000 (silicon covering) to $43,000 (TPO w/2.5" insulation and faccia replacement.)

There are so many questions and issues regarding particulars so detailed I hesitate to get into them here. Which makes me wonder…are there roofing associations in or around big cities? I wish I could get input from local roofing retirees…former roofers with experience and expertise without skin in the game!

Any suggestions?



You came to the correct place. Can we have a few pictures?

You bet! Thanks. I’ll try to upload…![Big%20house%20front%202–6%3A7%3A10|666x500]

All cathedral ceilings
With exposed homosote ceiling/decking?

Am i correct?
Or what is it?

You are going to drive yourself crazy with so many different bids. Talk to a reputable supplier, research through CCB and BBB if applicable, get the names of three reputable companies and find the one you trust. If a homeowner told me we were the 8th contractor they had contacted I would let them know we weren’t interested in the job.

It’s a 1958 split-level built into the side of the hill. 59.2 x 30 ft roof with a slight pitch and one gutter on the low side. The original roofing was tar and gravel. The ceiling is tongue-and-groove wood.

Well, I started with a list of 18 local roofers. 9 didn’t return my call. 3 stood me up. Met with 5. Got estimates from 4, from a silicon coating for $6000 to $43,000 for TPO with 3" insulation and faccia replacement.

TPO, EPDM, modbit, silicon, tar-and-gravel, ISO insulation 1/2 inch, 1 inch, 2 inch, 3 inch, manual, heat and/or adhesive sealing, replacement of faccia or not, gutter attachment, cost of access fee or not, cost of plywood for decking repairs, size/thickness of plywood, etc. There are so many particulars, it is difficult to compare.

it looks and sounds that your ceiling is also your roof decking.
Be careful, you dont want any fasteners of the new roofing to poke through your ceiling.

I see no mention of PVC.

I would look at PVC if I were you.

The good old time proven BUR like you already have is the one of the best flat roofs you can get depending on how it is applied.

Yes, thank you. I think the ceiling is part of the decking (photo.)

The original roof was tar and white gravel (BUR?) Given the house is 60+ years old now, would that be kind of heavy?

I went through my Dad’s old blueprints and couldn’t find specs forthe roof except these “Sheet Metal Details” (photo). Don’t know if this is useful or not…